fix invalid read of an address dues to the graphics window try to delete the scene viewer twice
fix invalid read of an address dues to the graphics window try to delete the scene viewer twice

git-svn-id: 4705079bc6b8aadf675e3696f5c015a6aa4916e3@5578 3c1deb5b-d424-0410-962d-aba41a686d42

OpenCMISS/zinc,hsorby/zinc,OpenCMISS/zinc,hsorby/zinc,hsorby/zinc,hsorby/zinc,OpenCMISS/zinc,OpenCMISS/zinc